1. Field of the Invention
The present invention relates to an ear probe for use in closed-loop caloric irrigation and, more particularly, to an improved probe including a disposable silicone rubber balloon for use with caloric irrigation apparatus.
2. Description of the Prior Art
The human species has evolved and developed an elaborate balance system to allow for proper relationship between its surroundings and an erect posture. The system is a complicated one, requiring integration of information from the visual system, the vestibular system, and the skeletal-muscular system.
For a patient complaining of dizziness and impaired balance, a disorder can exist in any of these systems. To determine the source of the disorder, many different tests are performed. In addition to the spontaneous nystagmus and postual reflex tests, a complex recording technique has been developed called electronystagmography (ENG). ENG provides for a permanent objective recording, obtained in a relatively standardized manner, of responses from the vestibular system.
In order to perform adequate tests utilizing ENG, the vestibular system must be stimulated to create the condition of dizziness and impaired balance. It has been determined that proper stimulation may be achieved by adding heat to or taking heat away from the inner ear. It is for this purpose that several caloric irrigators have been developed.
A conventional caloric irrigator consists of a fluid reservoir, a fluid pump, a heating and cooling system, and a conduit for conducting fluid, pumped by the pump, from the reservoir, through the heating and cooling system, to a probe insertible into the ear canal. While caloric irrigators are widely used, existing equipment has many disadvantages associated therewith. A basin or towel is required to catch the water flowing out of the ear, making the procedure difficult and awkward. The procedure requires trained personnel and it is virtually impossible to stimulate both ears simultaneously, which many experts say is a necessity for a meaningful test. Such a procedure is not applicable in the case of a patient with a perforated eardrum since the water will flow through the perforation. It is also difficult to measure a fixed stimulation parameter such as temperature, fluid volume, and flow rate.
To solve the above problems, it has been proposed by researchers in the Department of Otorhinolaryngology, School of Medicine, Keio University, Tokyo, Japan, to provide a closed-loop channel for conducting fluid from the reservoir to the ear and back to the reservoir. The proposed system consists of a water tank with a stirrer, a heating and cooling system, a temperature control system, a pump system with a timer, and a silicone ear canal balloon. The silicone balloon is inserted into the auditory canal and is made to adhere tightly to the canal wall by the pressure of the water as it is pumped from the reservoir, into the balloon, and back to the reservoir. Heat transfer to the ear canal is achieved through the wall of the balloon. Since the water does not directly contact the ear, the system can be used even with a perforated eardrum. Unilateral or bilateral simultaneous stimulation can be performed and the various parameters can be readily controlled.
Even with the above advantages of a system using an inflatable balloon, several problems still exist with the proposed apparatus. The balloon of the proposed system is a one-piece, molded part having an inlet and an outlet that are positioned side by side. This makes the balloon overly large, preventing its use with very small or partially obstructed ear canals. Furthermore, the one-piece construction is complex and expensive and the entire unit must be replaced periodically.
Generally speaking, the purpose of a probe is to maintain a precise temperature, for a given time, in the ear canal, as close to the ear drum as possible. Ear canals vary in size depending on age and physical structure of a patient so it is necessary to construct a probe that can be used in all subjects, thereby eliminating error by a technician. To maintain a given temperature in the ear canal, it is necessary to maintain a given fluid flow. Since the dimensions should be held to a minimum and flow to a maximum, the construction of a total probe is the key to feasibility.
The ear canal is sensitive to foreign objects. Therefore, the probe must be soft and of low mass so that placement can be done with the least amount of trauma to the patient. For sterilization purposes, the portion of the probe that goes into the ear should be replaceable. The probe construction should define probe placement relative to the ear so that tests are repeatable. Repeatability of probe placement in the ear canal is also important because total heat transfer is dependent on balloon contact. A probe satisfying all of these requirements has been unavailable heretofore.